The present invention relates to fuse clips, and more particularly, to cartridge fuse clips capable of rejecting improper fuses.
Cartridge fuses are available in a wide variety of current ratings and interrupting capacities (IC). At least in one case, cartridge fuses of the same current rating but of different interrupting capacities are of substantially the same physical size. Specifically, the current limiting, high IC class R cartridge fuse is essentially identical in physical dimensions to the non-current limiting, low IC class H cartridge fuse. Consequently, the class H and class R fuses are interchangeable insofar as the fuse clip is concerned. Obviously, they are not interchangeable from the standpoint of circuit protection. If a class H fuse is inadvertently inserted in a fuse clip installed in a circuit calling for class R fuse protection, a potentially hazardous situation is created. To discourage this, industry has resorted to keying one terminal of the class R fuse and a specially designed rejection fuse clip which accepts the keyed end terminal of a class R fuse but does not accept the unkeyed end terminal of a class H fuse. In the case of class R fuses having blade-type end terminals, keying is achieved by cutting a notch in one of the terminal blades. The rejection fuse clip is then provided with an interference member which is accommodated in the notch of a class R fuse terminal blade as it is inserted between the clip clamping arms. The interference member however engages the unnotched, smooth edge of a class H fuse terminal blade to obstruct its insertion between the clamping arms. Rejection fuse clips of this type are exemplified in U.S. Pat. Nos. 2,558,581; 3,858,058; and 4,037,917.
Since both class R and class H fuses are widely used, manufacturers are forced into the uneconomical proposition of having to manufacture and stock both the rejecting and the non-rejecting types of fuse clips. Since the fuse clips are assembled in electrical equipment prior to shipment, the equipment itself must also be stocked or, alternatively, the type of fuses the equipment is to utilize must be known at the time of assembly.
To mitigate the additional manufacturing expense engendered by the necessity of supplying both types of fuse clips, manufacturers have resorted to providing with the equipment a basic non-rejecting type of fuse clip capable of accepting both class H and class R cartridge fuses and offering a kit including a rejection member which is physically assembled to the basic fuse clip by the customer at the time the equipment is installed.
It is accordingly an object of the present invention to provide a fuse clip having improved field installable interference means for converting the fuse clip from a non-rejecting mode to a rejecting mode.
An additional object of the present invention is to provide a fuse clip of the above character, wherein the interference means may be assembled to the fuse clip in the field with minimal time and effort and without the necessity of tools.
A further object is to provide a fuse clip of the above character wherein the interference means, once installed, cannot be readily dismantled.
Still another object of the invention is to provide a rejecting type fuse clip of the above character which is inexpensive to manufacture and reliable in operation.
Other objects of the invention will in part be obvious and in part appear hereinafter.